Nickel cobalt sulfide Nanotube Array on Nickel Foam as Anode Material for Advanced Lithium-Ion Batteries

Study on Energy Storage of ZnCo2Sx Based on Sulfur Vacancy Modulation of Ion Transport Rate

Nowadays, high-rate, high-cycle anode materials for lithium batteries are a research hotspot, and defect engineering for electronic structure modulation is expected to be an effective strategy to improve electrochemical performance. In this paper, we controlled the concentration of ZnCo2S4 sulfur vacancies by regulating the hydrothermal time and performed density functional theory (DFT) calculations on ZnCo2S3.125 with vacancies. The results showed that ZnCo2S3.125 exhibited metallic properties, and the vacancies helped to accelerate the diffusion of carriers and improve the storage capacity. The discharge capacity of ZCS-6 initially reached 2,503.2 mAhg-1 in the first cycle, then maintained at 1,529.8 mAhg-1 after 200 cycles. The excellent cycling performance was attributed to the vacancies that enhanced the carrier transport and adsorption capacity of ZnCo2Sx. Notably, the sulfur vacancy-based surface defect strategy in this study had a greater impact on the electrochemical performance than the morphology optimization strategy.

A Review of Cobalt-Containing Nanomaterials, Carbon Nanomaterials and Their Composites in Preparation Methods and Application

With the increasing demand for sustainable and green energy, electric energy storage technologies have received enough attention and extensive research. Among them, Li-ion batteries (LIBs) are widely used because of their excellent performance, but in practical applications, the electrochemical performance of electrode materials is not satisfactory. Carbon-based materials with high chemical stability, strong conductivity, high specific surface area, and good capacity retention are traditional anode materials in electrochemical energy storage devices, while cobalt-based nano-materials have been widely used in LIBs anodes because of their high theoretical specific capacity. This paper gives a systematic summary of the state of research of cobalt-containing nanomaterials, carbon nanomaterials, and their composites in LIBs anodes. Moreover, the preparation methods of electrode materials and measures to improve electrochemical performance are also summarized. The electrochemical performance of anode materials can be significantly improved by compounding carbon nanomaterials with cobalt nanomaterials. Composite materials have better electrical conductivity, as well as higher cycle ability and reversibility than single materials, and the synergistic effect between them can explain this phenomenon. In addition, the electrochemical performance of materials can be significantly improved by adjusting the microstructure of materials (especially preparing them into porous structures). Among the different microscopic morphologies of materials, porous structure can provide more positions for chimerism of lithium ions, shorten the diffusion distance between electrons and ions, and thus promote the transfer of lithium ions and the diffusion of electrolytes.

Hydrogen Bubble-Directed Tubular Structure: A Novel Mechanism to Facilely Synthesize Nanotube Arrays with Controllable Wall Thickness

Nanowire arrays can be conveniently fabricated by electrodeposition methods using porous anodized alumina oxide templates. They have found applications in numerous fields. Nanotube arrays, with their hollow structure and much enhanced surface-to-volume ratio, as well as an additional tuning parameter in tube wall thickness, promise additional functions compared with nanowire arrays. Using a similar fabrication method, we have developed a facile and general method to fabricate metallic nanotubes (NTs). Using Ni NTs as a model system, the mechanism of the hydrogen-assisted NT growth was postulated and confirmed by controlling the hydrogen formation with conductive salts in an electrodeposition solution, which improves the H₂ concentration but prevents the large H₂ bubbles from blocking the nanochannel of a template. The controlled hydrogen generation forces the growth along the wall of nanochannels in the templates, leading to the NT formation. The magnetic properties can be controlled by the NT wall thickness, making these NTs useful for various applications.

Recent Advances of Bimetallic Sulfide Anodes for Sodium Ion Batteries

The high usage for new energy has been promoting the next-generation energy storage systems (ESS). As promising alternatives to lithium ion batteries (LIBs), sodium ion batteries (SIBs) have caused extensive research interest owing to the high natural Na abundance of 2.4 wt.% (vs. 0.0017 wt.% for Li) in the earth's crust and the low cost of it. The development of high-performance electrode materials has been challenging due to the increase in the feasibility of SIBs technology. In the past years, bimetallic sulfides (BMSs) with high theoretical capacity and outstanding redox reversibility have shown great promise as high performance anode materials for SIBs. Herein, the recent advancements of BMSs as anode for SIBs are reported, and the electrochemical mechanism of these electrodes are systematically investigated. In addition, the current issues, challenges, and perspectives are highlighted to address the extensive understanding of the associated electrochemical process, aiming to provide an insightful outlook for possible directions of anode materials for SIBs.

Constructing MoS2/CoMo2S4/Co3S4 nanostructures supported by graphene layers as the anode for lithium-ion batteries

With the increasing energy demand, it is very urgent to develop new anode materials for lithium ion batteries (LIBs). Designing nanostructures and constructing multicomponent metal sulfides are vital for enhancing the electrochemical performance. This study reports a new synthetic method to construct MoS2/CoMo2S4/Co3S4 nanostructures supported by graphene. A key step in the process, high temperature annealing, promotes the interdiffusion of metal sulfides to form multicomponent metal sulfides and establishes a strong C-S bond between the MoS2/CoMo2S4/Co3S4 nanostructure and graphene. The unique nanostructure and synergistic effects between the conductive graphene and the MoS2/CoMo2S4/Co3S4 nanostructure endows the material with good lithium storage. As a result, it exhibits a good rate performance (360 mA h g-1 at 10 A g-1) and a high specific capacity (770 mA h g-1 at 0.2 A g-1). This study provides a unique method to construct promising anode materials for the application of LIBs.

A cellulose substance derived nanofibrous CoS–nanoparticle/carbon composite as a high-performance anodic material for lithium-ion batteries

Nanofibrous CoS–nanoparticle/carbon composite derived from a cellulose substance was fabricated, showing enhanced electrochemical performances as an anodic material for lithium-ion batteries.

Synthesis of NiGa2S4-rGO on nickel foam as advanced electrode for flexible solid-state supercapacitor with superior energy density

Pseudocapacitive electrode materials employed in supercapacitors may bring in high energy density (ED) and specific capacitance (C_sc), which are critical for their practical applications. Accordingly, logical design of advanced electrode materials is highly demanded to progress high-performance supercapacitors. Here, for the first time, we suggest a straightforward route for the synthesis of NiGa₂S₄-rGO as an advanced cathode material supported on nickel foam (NF) for employed in flexible solid-state asymmetric supercapacitors (FSASCs). Due to an abundant ratio of active sites and large surface area of the NiGa₂S₄-rGO advanced material, the as-prepared NiGa₂S₄-rGO/NF electrode illustrates considerable electrochemical properties including remarkable specific capacitance (C_sc) of 2124.34 F g^-1 with excellent rate capability of 73%, and exceptional durability, which are better than NiGa₂S₄/NF and previously reported transition metal sulfides (TMSs). Furthermore, for the first time a pseudocapacitive advanced anode material of FeSe₂-rGO have been successfully fabricated on a nickel foam (NF) substrate by a facile strategy. Element Selenium as the favorable element was offered into the Fe for enhancement and adjustment of the anode material electrochemical performance. The FeSe₂-rGO/NF advanced anode electrode presents satisfactory electrochemical properties containing an exceptional specific capacitance (C_sc) of 432.40 F g^-1, significant rate performance of 57.84% and superior durability, which are better than FeSe₂/NF electrode and previously studied Fe-based anode material. Considering the remarkable electrochemical performance of the as-prepared pseudocapacitive advanced electrode materials, a FSASC based on the NiGa₂S₄-rGO/NF as the cathode electrode and FeSe₂-rGO/NF as the anode electrode was assembled. The FSASC device delivers superior C_sc of 341.20 F g^-1, outstanding energy density (ED) of 121.31 W h kg^-1, remarkable cycle stability (only 7.30% damage after 5000 charge/discharge (CD) cycles).

Carbon nanofibers (CNFs) supported cobalt- nickel sulfide (CoNi2S4) nanoparticles hybrid anode for high performance lithium ion capacitor

Lithium ion capacitors possess an ability to bridge the gap between lithium ion battery and supercapacitor. The main concern of fabricating lithium ion capacitors is poor rate capability and cyclic stability of the anode material which uses sluggish faradaic reactions to store an electric charge. Herein, we have fabricated high performance hybrid anode material based on carbon nanofibers (CNFs) and cobalt-nickel sulfide (CoNi₂S₄) nanoparticles via simple electrospinning and electrodeposition methods. Porous and high conducting CNF@CoNi₂S₄ electrode acts as an expressway network for electronic and ionic diffusion during charging-discharging processes. The effect of anode to cathode mass ratio on the performance has been studied by fabricating lithium ion capacitors with different mass ratios. The surface controlled contribution of CNF@CoNi₂S₄ electrode was 73% which demonstrates its excellent rate capability. Lithium ion capacitor fabricated with CNF@CoNi₂S₄ to AC mass ratio of 1:2.6 showed excellent energy density of 85.4 Wh kg⁻¹ with the power density of 150 W kg⁻¹. Also, even at the high power density of 15 kW kg⁻¹, the cell provided the energy density of 35 Wh kg⁻¹. This work offers a new strategy for designing high-performance hybrid anode with the combination of simple and cost effective approaches.

Nanostructured materials on 3D nickel foam as electrocatalysts for water splitting

Highly efficient and low-cost electrocatalysts are essential for water spitting via electrolysis in an economically viable fashion. However, the best catalytic performance is found with noble metal-based electrocatalysts, which presents a formidable obstacle for the commercial success of electrolytic water splitting-based H₂ production due to their relatively high cost and scarcity. Therefore, the development of alternative inexpensive earth-abundant electrode materials with excellent electrocatalytic properties is of great urgency. In general, efficient electrocatalysts must possess several key characteristics such as low overpotential, good electrocatalytic activity, high stability, and low production costs. Direct synthesis of nanostructured catalysts on a conducting substrate may potentially improve the performance of the resultant electrocatalysts because of their high catalytic surface areas and the synergistic effect between the electrocatalyst and the conductive substrate. In this regard, three dimensional (3D) nickel foams have been advantageously utilized as electrode substrates as they offer a large active surface area and a highly conductive continuous porous 3D network. In this review, we discuss the most recent developments in nanostructured materials directly synthesized on 3D nickel foam as potential electrode candidates for electrochemical water electrolysis, namely, the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). We also provide perspectives and outlooks for catalysts grown directly on 3D conducting substrates for future sustainable energy technologies.

Chemical synthesis of hierarchical NiCo2S4 nanosheets like nanostructure on flexible foil for a high performance supercapacitor

In this study, hierarchical interconnected nickel cobalt sulfide (NiCo₂S₄) nanosheets were effectively deposited on a flexible stainless steel foil by the chemical bath deposition method (CBD) for high-performance supercapacitor applications. The resulting NiCo₂S₄ sample was characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and electrochemical measurements. XRD and X-ray photoelectron spectroscopy (XPS) results confirmed the formation of the ternary NiCo₂S₄ sample with a pure cubic phase. FE-SEM and HR-TEM revealed that the entire foil surface was fully covered with the interconnected nanosheets like surface morphology. The NiCo₂S₄ nanosheets demonstrated impressive electrochemical characteristics with a specific capacitance of 1155 F g⁻¹ at 10 mV s⁻¹ and superior cycling stability (95% capacity after 2000 cycles). These electrochemical characteristics could be attributed to the higher active area and higher conductivity of the sample. The results demonstrated that the interconnected NiCo₂S₄ nanosheets are promising as electrodes for supercapacitor and energy storage applications.

Metal-Organic Framework Template Synthesis of NiCo2S4@C Encapsulated in Hollow Nitrogen-Doped Carbon Cubes with Enhanced Electrochemical Performance for Lithium Storage

Owing to its richer redox reaction and remarkable electrical conductivity, bimetallic nickel cobalt sulfide (NiCo₂S₄) is considered as an advanced electrode material for energy-storage applications. Herein, nanosized NiCo₂S₄@C encapsulated in a hollow nitrogen-doped carbon cube (NiCo₂S₄@D-NC) has been fabricated using a core@shell Ni₃[Co(CN)₆]₂@polydopamine (PDA) nanocube as the precursor. In this composite, the NiCo₂S₄ nanoparticles coated with conformal carbon layers are homogeneously embedded in a 3D high-conduction carbon shell from PDA. Both the inner and the outer carbon coatings are helpful in increasing the electrical conductivity of the electrode materials and prohibit the polysulfide intermediates from dissolving in the electrolyte. When researched as electrode materials for lithium storage, owing to the unique structure with double layers of nitrogen-doped carbon coating, the as-obtained NiCo₂S₄@D-NC electrode maintains an excellent specific capacity of 480 mAh g^-1 at 100 mA g^-1 after 100 cycles. Even after 500 cycles at 500 mA g^-1, a reversible capacity of 427 mAh g^-1 can be achieved, suggesting an excellent rate capability and an ultralong cycling life. This remarkable lithium storage property indicates its potential application for future lithium-ion batteries.

Triple-Confined Well-Dispersed Biactive NiCo2S4/Ni0.96S on Graphene Aerogel for High-Efficiency Lithium Storage

Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clay compounds, have attracted increasing interest in electrochemical energy storage, in the main form of LDH precursor-derived transition metal oxides (TMOs). One typical approach to improve cycling stability of the LDH-derived TMOs is to introduce one- and two-dimensional conductive carbonaceous supports, such as carbon nanotubes and graphene. We herein demonstrate an effective approach to improve the electrochemical performances of well-dispersed biactive NiCo₂S₄/Ni_0.96S as anode nanomaterials for lithium-ion batteries (LIBs), by introducing a three-dimensional graphene aerogel (3DGA) support. The resultant 3DGA supported NiCo₂S₄/Ni_0.96S (3DGA/NCS) composite, obtained by sulfuration of NiCo-layered double hydroxide (NiCo-LDH) precursor in situ grown on the 3DGA support (3DGA/NiCo-LDH). Electrochemical tests show that the 3DGA/NCS composite indeed delivers the greatly enhanced electrochemical performances compared with the NiCo₂S₄/Ni_0.96S counterpart on two-dimensional graphene aerogel, i.e., a high reversible capacity of 965 mA h g^-1 after 200 cycles at 100 mA g^-1 and especially a superlong cycling stability of 620 mA h g^-1 after 800 cycles at 1 A g^-1. The enhancements could be ascribed to the compositional and structural advantages of boosting electrochemical performances: (i) well-dispersed NiCo₂S₄/Ni_0.96S nanoparticles with interfacial nanodomains resulting from both the dual surface confinements of the 3DGA support and the crystallographic confinement of NiCo-well-arranged LDH crystalline layer, (ii) an appropriate specific surface area and a wide pore size distribution of mesopores and macropores, and (iii) highly conductive 3DGA support that is measured experimentally by using electrochemical impedance spectra to underlie the enhancement. Our results demonstrate that the tunable LDH precursor-derived synthesis route may be extended to prepare various transition metal sulfides and even transition metal phosphides for energy storage with the aid of tunable cationic type and molar ratio.